The author examined on the chief and heterogene reaction and the local anaphylactic phenomenon in the antiserum, immunized the rabbit by using the cow serum as the antigen, and obtained the following conclusion. 1. In the antiserum, its antigen is cow serum, there has been seen the specific and the unspecific heterogene precipitation reactions. The unspecific heterogene reaction was most strongest when the goat serum, the closed relation of cow serum, is used; stronger next when guinea pig and horse serums are used; and was in proportion to the frequency of injection. 2. Unspecific heterogene reaction was strong when serum euglobulin and pseudoglobulin are used as antigen and then the specificity of serum albumin was very strong. 3. The loc...